Physiology Of The Teeth And Its Supporting Structures PDF

PHYSIOLOGY OF THE TEETH AND ITS SUPPORTING Lecture by: Irene Joy Guevarra-Cesante, DMD, MBA, MSc TEETH Major Functions of the teeth ◦ It incise food and reduce food during mastication ◦ They help sustain themselves in the dental arches by assisting in the development and protection...

PHYSIOLOGY OF THE TEETH AND ITS SUPPORTING Lecture by: Irene Joy Guevarra-Cesante, DMD, MBA, MSc TEETH Major Functions of the teeth ◦ It incise food and reduce food during mastication ◦ They help sustain themselves in the dental arches by assisting in the development and protection of tissues that support them ex: physiologic mesial driftng  Importance of teeth ◦ Good teeth makes one more physically attractive ◦ Good diction is an asset and correct speech is made possible by the normal development of teeth and jaws ◦ Psychologically physical and mental concentration is aided by clenching the tooth firmly during almost any activity CROWN OF THE TEETH  The Crown ◦ part of the tooth that we see if we look into the mouth ◦ The anatomic crown extends to below the margin of the gum while the clinical crown is just the visible part of the tooth. ◦ The anatomic crown always has the same size, but the clinical crown may vary in size. ◦ anterior teeth have incisal ridges or edges while posterior teeth present cusps Anterior Teeth Crown Posterior Teeth Crown  Root of the Teeth ◦ covered with cementum ◦ the length and number of roots depends on the size and function of the teeth  PROTECTIVE FUNCTIONAL FORMS OF THE TOOTH CROWN Proximal contact area (PCA) ◦positive contact relation mesially and distally of one tooth with another while they are on their respective position in the dental arch  Proximal contact area (PCA) importance ◦ it serves to keep food from packing in between the teeth ◦ it helps to stabilize the dental arches by the combined anchorage of all the teeth in either arch, if in positive contact with each other. PCA can be observed from two aspects ◦labial/buccal aspects -will demonstrate the relative position of the contact areas cervico-incisallyor cervico- occlusally  PCA can be observed from two aspects ◦incisal/occlusal aspects will show the relative position of the contact areas labio-lingually or bucco-lingually Interproximal space ◦ they are formed by the proximal surfaces in contact ◦ are triangularly shaped spaces in between teeth and normally are filled by the gingival tissue ◦ there is normally a separation of 1-1.5 mm between the enamel and alveolar bone  Embrasures ◦ when two teeth in the same arch are in contact, their curvatures adjacent to the contact areas forms spillway spaces called embrasures Purposes: ◦ -it makes a spillway for the escape of food during mastication ◦ -it prevents food from being forced through the contact area  Types of Embrasure Incisal/Occlusal Labial/Buccal/Lingual Cervical ridges ◦ facial and lingual contours at the cervical thirds ◦ approximately 0.5 mm is the normal curvature from the cementoenamel junction (CEJ) to the crest of the contour Cervical ridges physiologic importance ◦ holds the gingiva under definite tension ◦ protects the gingival margins by deflecting food material away from the margins during mastication effect of the absence or minimal curvature ◦ gingival tissue may be driven apically resulting to gum recession and possible pathologic changes ◦ effect of the too much curvature ◦ gingiva is protected too much and loses tissue “tone” under the exaggerated contour ◦ food material and debris will be packed around the gingiva ◦ stagnation of foreign material leads to chronic inflammation of the gingiva  Curvatures of the cervical lines (CEJ) ◦the curvature of the cervical line of most teeth will be approximately 1 mm less distally than mesially ◦normal attachment follows the curvature of the CEJ if the teeth are in normal alignment and contact  ◦ PERIODONTAL LIGAMENT ◦ CEMENTUM Supporting ◦ ALVEOLAR PROCESS Structures ◦ PULP ◦ GINGIVA PERIODONTAL LIGAMENT ◦dense connective tissue attaching the tooth to the alveolar bone ◦thickness varies between 0.1- 0.25 mm Functions of Periodontal Ligament supportive and protective ◦PDL acts as a shock absorbing making sure the occlusal forces are well distributed and would not cause trauma to the teeth ◦formative ◦reaction from the PDL could signal the activation of osteoblasts, cementoblasts, and fibroblasts Functions of Periodontal Ligament sensory ◦PDL contains both sensory and autonomous nerve endings which give it the ability to estimate the amount of pressure during mastication and to identify which tooth is being percussed nutritive ◦due to the presence of blood supply from the branches of the alveolar and interradicular arteries Periodontal Ligaments Blood Supply: Nerves: MOBILITY: 1.Branches of alveolar Contains both 1st degree artery less than 1mm sensory and 2. Branches of interradicular artery autonomic 3. Gingival vessels that nerve endings 2nd degree enter the 1.1-2mm periodontal ligament in the crestal 3rd degree Region more than 2mm  Principal periodontal fiber groups ◦transseptal fibers embedded into the cementum of adjacent teeth and extends interproximallyover the alveolar crest ◦alveolar crest fibers extends obliquely from the cementum beneath the junctional epithelium to the alveolar crest  Principal periodontal fiber groups ◦horizontal fibers extends at right angle to the long axis of the tooth between cementum and alveolar bone ◦oblique fibers largest group of principal periodontal fibers, extending from the cementum obliquely to the alveolar bone Principal periodontal fiber groups ◦ apical fibers radiates from the apical cementum toPhysiology the alveolar bone of the Teeth and Its Supporting at the base of the socket ◦ interradicular fibers courses over the crest of the interradicular septum in the furcationsof multirooted teeth Cementum ◦ mineralized connective tissue that covers the roots of teeth ◦ contains cementoblasts, cementoclasts, and cementocytes Functions: -to attach the periodontal ligament fibers to the teeth Classification of Cementum  Types of Cementum Cells: Cementoblasts Cementoclasts cementocytes  DEVELOPMENTAL AND ACQUIRED ANOMALIES ASSOCIATED WITH CEMENTOGENESIS Enamel Projections Hypercementosis Enamel Pearls Cementicles ALVEOLAR BONE ◦ part of maxilla and mandible that forms and supports the teeth ◦ contains osteoblasts, osteoclasts, and osteocytes Parts of Alveolar Bone alveolar bone proper ◦ consists of thin lamella of bone immediately surrounding the root ◦ radiopaque lamina dura in radiograph supporting bone ◦ surrounds the alveolar bone proper and provides additional functional support Pulp ◦ consists of vascular connective tissue contained within the rigid dentinal walls ◦ contains fibroblasts (for collagen formation, odontoblasts, and defensive cells Functions of the Pulp ◦ Formative – forerunner of dentin. ◦Nutritive ◦Sensory ◦Defensive Composition of Pulp CELLS ◦ Fibroblasts ◦ Odontoblasts ◦ Defensive cells (histiocytes wandering cells, undifferentiated mesenchymal cells, polymorphonuclear leukocytes, lymphocytes, plasma cells, eosiniphils) GROUND SUBSTANCE ◦ Protein associated with glycoproteins ◦ Acid mucopolysaccharides Composition of Pulp FIBERS ◦ Collagen fibers BLOOD VESSELS ◦ Either arteries or arterioles enter the pulp at its apical termination and course coronally, increasing and branching into capillaries adjacent to the odontoblastic layer NERVES ◦ Enter the pulp at its apical segment with the afferent blood vessels either as accompanying individual units or as intimately associated nervesheaths ◦ Majority of sensory receptors on the dental nerves are free nerve endings extirpated pulp tissue from the pulp chamber and root canal of an anterior tooth  Pulpal response to aging ◦ decrease in cellular components ◦ dentinal sclerosis ◦ decrease in the number and quality of blood vessels and nerves ◦ reduction in size and volume of the pulp owing to continued dentin deposition and reparative dentin formation ◦ increase in number and thickness of collagen fibers ◦ increase of pulp stones and dystrophic mineralizations GINGIVA ◦ part of the oral mucosa that covers the alveolar processes and surrounds the cervical region of the teeth Regions of Gingiva marginal gingiva/gingival margin/unattached gingiva ◦ border of the gingiva surrounding the teeth in a collar fashion attached gingiva ◦ firm, resilient and tightly bound to the underlying alveolar periosteum Regions of Gingiva interdental papilla/gingiva ◦ occupies the interproximal space between the areas of adjacent tooth contact Layers of gingival epithelium oral epithelium (OE) ◦ the outer epithelium that covers the crest and outer surface of the marginal gingiva and the surface of the attached gingiva ◦ keratinized Layers of gingival epithelium ◦sulcular epithelium (SE) ◦lines the gingival sulcus ◦a thin layer of non-keratinized squamous epithelium that extends from the coronal limit of the junctional epithelium to the crest of the gingival margin Layers of gingival epithelium junctional epithelium (JE) ◦comprises a collar-like band of non-keratinized squamous epithelium ◦the tooth is reinforced by the gingival fibers that brace the marginal gingiva against the tooth surface  Layers of gingival epithelium gingival epithelium also differentiates to form 2 epithelial types ◦the epithelium which covers the outer surface of the marginal gingiva and the attached gingiva and comprises keratinized or parakeratinizedlayers ◦the gingival sulcular epithelium which is usually non-keratinized Groups of gingival fibers dentogingivalgroup ◦ embedded into the cementum just beneath the epithelium at the base of the gingival sulcus ◦ the fibers then spread in fan- like fashion into the periosteum, crest of interdental gingiva, and attached gingiva  Groups of gingival fibers dentoperiostealgroup ◦fibers extend to the outer surface of the alveolar bone alveologingivalgroup ◦fibers extend from the alveolar crest to the lamina propria of free and attached gingiva  Groups of gingival fibers circular group ◦ fibers that encircle the tooth in a ring-like fashion semicircular group ◦ fibers that emanate from the cementum near the CEJ, cross the free gingival margin, and insert into a similar position on the tooth’s opposite side  Groups of gingival fibers transseptal group ◦ forms horizontal bundles between the cementum of approximating teeth into which they are embedded ◦ they lie in the area between the epithelium at the base of the gingival sulcus and the crest of the interdental bone  Groups of gingival fibers transgingival group ◦ seen in and around the teeth within the attached gingiva intergingivalgroup ◦ seen within the attached gingiva adjacent to the basement membrane extending mesiodistally, providing support and contour for the attached gingiva  Lamina propria ◦ the connective tissue of the gingiva that is densely collagenous with the following layers: ◦ a papillary layer subjacent to the epithelium consisting of papillary projections between the epithelial rete pegs ◦ a reticular layer connecting with the periosteum of the alveolar bone Morphology of Gingiva color ◦ coral pink pigmentation ◦ due to melanocytes occurs as a diffuse deep purple discoloration or irregular brown pigmented areas  Morphology of Gingiva contour ◦ depends on the following: ◦ shape of the teeth ◦ alignment of teeth within the arch ◦ location and size of the proximal contact between adjacent teeth ◦ dimensions of the facial and lingual gingival embrasures ◦ appears as a “scalloped line” on the facial and lingual (marginal gingiva)  Gingival morphology consistency ◦ firm and resilient (attached to underlying periosteum) surface texture ◦ “stippled” appearance on the attached gingiva (less prominent on the lingual and there may be none in some mouth) ◦ lost stippling is an early sign of gingivitis Gingival morphology location ◦ at the level of the cementoenamel junction (CEJ)